From: Jeff King <peff@peff.net>
Date: Mon, 11 Feb 2019 20:20:00 GMT
Subject: Re: [PATCH 1/8] tests: define GIT_TEST_PROTOCOL_VERSION
Message-ID: <20190211201959.GA9072@sigill.intra.peff.net>
In-Reply-To: <6e0c6aa9a71d4192591ed406735684cd15a0e3b9.1549411880.git.jonathantanmy@google.com>

On Tue, Feb 05, 2019 at 04:21:15PM -0800, Jonathan Tan wrote:

> Define a GIT_TEST_PROTOCOL_VERSION environment variable meant to be used
> from tests. When set, this ensures protocol.version is at least the
> given value, allowing the entire test suite to be run as if this
> configuration is in place for all repositories.
> 
> As of this patch, all tests pass whether GIT_TEST_PROTOCOL_VERSION is
> unset, set to 0, or set to 1. Some tests fail when
> GIT_TEST_PROTOCOL_VERSION is set to 2, but this will be dealt with in
> subsequent patches.

Makes sense. The "at least" part made me scratch my head at first, but
your explanation in response to Ævar made sense.

Two minor nits:

> diff --git a/protocol.c b/protocol.c
> index 5664bd7a05..c7a735bfa2 100644
> --- a/protocol.c
> +++ b/protocol.c
> @@ -42,6 +42,10 @@ static const char *format_protocol_version(enum protocol_version version)
>  enum protocol_version get_protocol_version_config(void)
>  {
>  	const char *value;
> +	enum protocol_version retval = protocol_v0;
> +	const char *git_test_k = "GIT_TEST_PROTOCOL_VERSION";
> +	const char *git_test_v = getenv(git_test_k);

We've discussed recently how the return value from getenv() isn't
stable. It looks like we could assign it much closer to the point-of-use
here (which still isn't 100% foolproof, but I think is something we
could encourage as a general pattern, and mostly works due to our
ring-buffer technique).

I.e., right before this conditional:

> +
> +	if (git_test_v && strlen(git_test_v)) {

It's more idiomatic in our code base to check for a non-empty string as:

  if (git_test_v && *git_test_v)

though obviously that's pretty minor.

-Peff